Section 3A. After December thirty-first, nineteen hundred and twenty-four, all deposits of funds of public service corporations, except common carriers under the supervision of the interstate commerce commission, shall be made by the officers of the corporations in national banks, duly chartered trust companies, savings banks, co-operative banks or federal savings and loan associations; but the foregoing provision shall not apply to any deposit for a period of not more than sixty days made for the purpose of meeting obligations maturing within said period or to any deposit for a similar period of time resulting from the sale of obligations or securities.